Fabrication of electrodes for electron discharge devices



May 22, 1956 s. o. EKSTRAND ET AL 2,746,123

FABRICATION OF ELECTRODES FOR ELECTRON DISCHARGE DEVICES Original FiledAug. 5, 1949 3 Sheets-Sheet l INVENTORS f g wgf A TTORNEV May 22, 1956s. o. EKSTRAND ET AL 2,746,123

FABRICATION OF ELECTRODES FOR ELECTRON DISCHARGE DEVICES Original FiledAug. 3, 1949 5 Sheets-Sheet 2 FORM PLATE BLANK WE L 0 TWO ELAN/(STOGETHER H VDROGE N HEA T TREATMENT BUMP/ N G OPERA T/ ON COA T/NG TREATMENT S. O. EKSTRAND V. L. RONC/ A TTORNE Y United States PatentFABRKEATIGNOF ELECTRODES FQR ELEGTRON DISCHARGE DEVICES Stpre 0.Elsstrand, Bctlilehern, and Victor L. Ronci, Zionsville,-Pa., assignorsto Bell Telephone Laboratories, Incorporated, New York, N. Y., acorporation of New York r gi app a i n u tist .3 Se ia la- 193 3 newPatent No; 2,592,549, dated April'l 5, 1952. Divided and'thisapplication May 19, 1951; Serial No. 227,214

3 Qlaims. (Cl. 291-2543) This invention relates to electron dischargedevices and we r tt etletiy t e eet es e stmeta es, spe ia eees shit-s ae e she siey eeshi e ri ett en i a d is on of applica ion Se ia N9- es-st file Ahs s 4 ew Patent Ne- 5 549, reeted pr 1 1 2- It i W ll ithew 9eu e th t th op in eher eter st e Qt e eetre sehe e d v es are d p n-eat 1 99 1 the e e esi s a hs end a e t eul r adv nta e us eher et ie mhe lized by ma n th s snae n s smell- Fo examp elese i t le t ede pa inesp .ei lly smell p c be w en t e d an mode. l ads to sm ll voltage t eand sh p e fi c a a te i t cs- The realization of small spacings,however, entails manifold pra c l d fi e lt Sp fic l y, i i t u no on yto o a n a e a ni e 'e e trede spa in s bu a s o m in s h sp c n du ngope a on o he .d Fur h the ea za o un or i y of pro uc in quantitymanufacture of electron discharge deViCes having closely adjacentelectrodes involves obvious comple T gen ral p e lem inv lve may bappreciated when it is noted that in particular triodeshaving a nominalgrid-to-anode spaci g Of the order of 0.0085 inch the permissibletolerances in this spacing 1Q meet prescribed operating requirements areof the order of :01101 inch.

One general object of this invention is to improve the structure andperformance characteristics of electron discharge devices. andespecially of such devices having very closely spaced electrodes. Morespecifically, objects of this invention are to facilitate the attainmentof prescribed small interelectrode spacingsfto expedite -the-fabricationof devices including very closely spaced electrodes, to minimizevariations in the interelectrode spacings during operation of thedevices, and/to enhance uniformity of product in the quantitymanufacture of such devices.

In accordance with one feature of this invention, an anode for electrondischarge devices of the type having portions or sections on oppositesides of another electrode, such as a cathode or grid, is constructed oftwoparallel plate sections having spaced embossments, the embossments onthe two sections being jointed inabutting relation to fix the spacingbetween the sections.

In accordance with another feature of this invention, the anode sectionsare provided with extensions or cars constructed and arranged so thatthey may be readily associated with spacer members, such asinsulatingdiscs, to mount and position the'anode in prescribed relation to otherelectrodes and to maintain the anode position during operation of thedevice.

In accordance with a further feature of this invention the anode, afterassembly, is heat treated to relieve stresses resulting from the joiningof the anode sections, whereby these. sections maintain their properrelationship.

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hi se et i ee with a ti urthe f ature ei this tivetltion the apodesections are subjected to a bumping op ran to ns r uniferhiity s ras a de teilelisiii tween the plate sections.

These aud other desirable features are incorporated in one illustrativeembodiment of this invention'in a twin ede i Whieh the twi e e etie e ms a e in sted in parallel relation between mica spacers supported inspaced relation on'two rigid posts extending from an inwardly projectingstern, the spacers being attached to e s a b le The w atho e a e hea ertype rectangular-shaped sleeves with a pair of embossments on the shortsides at opposite ends to locate the cathodes properly between thespacers. The insulated heater elements are mountedby a pair ofhorizontal Wires connecting the heaters in parallel with each wireattached to a vertical lead-in wire in the stem. The cathodes areseparately connected to other lead-in wires in the stem. The grids arewound .on side rods of the swedged type and the windings or laterals arein parallel relation to the greater dimensions or" the cathode surface.The anode is tormed of two parallel plates with circular emess l ts ad ae th engi i d h d e eme sin i a h P ate p etest i w rd nd a al d withthe cooperating embossrnents of the other plate to which they arelocally welded. The anodes are also provided with different sized pairsof cars at each corner to loclr the anodes in the mica spacers, thelarge ears mounti ig ill? odes from the spacers and one of the narrowerears forming a lead connection for each anode. I

Eurtheriu one illustrative procedure for preparing the auode strpcturesin accordance with this invention whereby they will have very accuratespacing, the anode plates ar fi s forme ith t essments a d e T embossmerts are then aligned with cooperating embossments on the other plate'andthe two welded together, tollowing which the welded anode structure ishydrogen heat treated to obtain a stress-free surface. The anodestructure is then bumped i a bumping die whereby the ehihs siheh e itier u hed t tain a uniform spacing between the two anode plate sections.The anode is then coated with a blackrbody gas-absorbing ea i ic- Acomplete understanding of these and other desirable fea r s Qt this i hi i ma e ai e si e tion of the following detailed. description and theaccomr eeyi s d aw s, in w ie Fig.1 is an elevational view of a twintriode electron iiisehsese evi e embesi ie a s ed structure illustratetive of invention, a portion of the enclosing vessel heies .h eh i the tsh he t rnal assembly;

ie 2 i a de iew n e ev t on of the e e e t a mounted in the stem of thedevice shown in Fig. l;

. Fig. 3 is asectional view of the device taken along in v f Fig. 4 isanelevational view of an anode section illustra at o e emhe i eet o sinventi Fig. 4A is a sectional view along line 4A4A of Fig. .4;

a 5 i a en view f a di se n t p p at h Qt" t e suede tust r n eese deiwi this n i F 5B is? side e f t d f F l'sig. 6=is a perspective view ofone die member ofl ig. 5, showing the anode structure mounted on themandrel;

Fig. 7 is a diagram' illustrating the steps to be taken in-thep er re ofhe an d s r e nd Fig.8 is asectional view of one triode structure takenalong l ne f 2- et riie eth thaw the e et ed as mb is mo nte e e es it vse 10 h ch s ea e n e bas 1: p o ded w th a p ur lity of te m nal Pins.12.

mounted in parallel relation in a circle. The electrode unit, which forpurposes of illustration is shown as a twin composed of parallel plates13 and 14, joined together by embossments 15, and encompassing cathode16, a helical grid 17 which is Wound on support rods'18, and a cathodeheater 19, best seen in Fig. 8. The electrodes are mounted betweeninsulating spacer discs 23 and 24 and are connected through the stem tothe pins 12 by appropriate leads. Thus the two grids 17 areindependently connected to two pins 12 by the leads 25 attached each toa grid rod 18, and the cathodes 16 are connected to pins 12 by two leads26, the leads being composed of a ribbon portion attached to theelectrode and a wire portion attached to the pin, the two portions beingjoined together as by welding. The heater elements 19 are connected totwo leads 28 by cross wires 27, the two heater elements thus beingconnected in parallel. The insulating discs 23 and 24 are supported inspaced relation by a plurality of rigid posts 32, 33,

34 and 35, two of which extend from the inwardly pro jecting stem 20.The insulating discs are attached to the posts as by eyelets 36. A shortlead 37 connects one anode to the post 32 and another lead 37 the otheranode to post 35, the two posts extending into the stem 20 and being inturn connected to appropriate pins 12. Thus the cathodes, grids andanodes are individually connected externally through the pins 12 forapplying suitable potentials to the various electrodes.

The cathode 16, as shown best in Fig. 8, comprises a rectangular sleeve,as of nickel, which is coated on the outside with electroemissivematerial, such as a finely divided barium-strontium-calcium carbonate inamyl acetate solution of nitrocellulose plasticized with butylcellosolve. The grids 17 may be of the swedge type with laterals formedof molybdenum wire and gold-plated to reduce emission from the grids.The spacer discs 22 and 23 may be of mica.

An insulation disc 40, which may also be of mica, is supported above theelectrode assemblies by the posts 32, 33, 34, and 35, to which it isattached by eyelets 41. Side strips 42, which may also be of mica, areattached to the disc 40 and held in position by cars 43 evenly spacedaround the periphery of the disc 40. The disc 40 and side strips 43serve to prevent vibration of the top endof the electrode assembly.

' A getter wire 44 is mounted by a getter support assembly 45 attachedto one of the posts, such as 32.

The anode sections 13 and 14, as shown in Fig. 4, are provided withditferent sized pairs of cars 46 and 47 to lock the anodes in the spacerdiscs 23 and 24. The large ears 46 provide the rigid mounting of theplates and one of the narrow ears 47 is connected to lead 37 to providethe connection to the post and thus the pin '12. While only one ear'47is used for each anode the plates are stamped with the ears at allcorners to simplify the assembly and thereby avoid selection of partsfor the fabrication of the anodes. The anode sections are also formedwith end flanges 53 between the ears 46 at both ends of the section.

The various electrodes are supported in fixed position by the spacerdiscs 23 and 24, as best seen in Fig. 3 with reference to disc 23. Thedisc is provided with apertures 48 through which the narrow ears 47extend and with apertures 49 and 50 through which the larger ears 46extend. The apertures 49 are slightly larger-than the ears 46 so thatthe ears float in them, but the apertures 50 are of almost the samewidth as the ears 46 so that the ears are tightly held thereby. A shortsection of the ears 46 is flat and parallel to the plane of the anodesection to accomplish location in the disc 23. The remaining parts ofthe ears 46 are bent slightly to facilitate entrance into the respectiveslots in the disc 23 and to clearly define the ear sections in whichparallelism must be maintained. Apertures 51 are provided in the disc 23through which the cathode sleeve 16 closely fits, the sleeve beingformed with embossments 52, best seen'in Fig. 2, directly beneath thedisc 23 and above the disc 24, to hold the cathode firmly in position.Other apertures are provided in the disc members through which the postsand rods 18 extend. 1

In the construction of the anode, each anode section 13 and 14 is firstblanked and formed in a press, the embossments 15, ears 46 and 47, andend flanges 53 being formed with the sections. The sections are thenplaced in a Welding jig in which the sections can be rapidly aligned.The embossments 15 on section 13 are then weldedto the embossments onsection 14; all six welds'may be'made at one time, or singly ifpreferred. The welded assembly is then heated treated in a hydrogenatmosphere to relieve all strains from the welding operation and theoriginal forming operation. It has been found advantageous to heat theassembly at around 1000 C. for about 10 to 15 minutes.

It has also been found advantageous that the assembly in this stage havea spacing between the two sections 13 and 14 which is slightly largerthan that required by the tube geometry. It has been found that thediiferent assemblies after the heat treatment have larger variations inthe spacing between sections from one assembly to the next than can betolerated. In order to insure uniformity of spacing in the assembliesand parallelism between the sections 13 and 14 each assembly is subjectto a bumping operation in a die such as shown in- Figs. 5 and 6.

The bumping die shown in Figs. 5 and ,6 comprises an upper die member 57and a lower die member 58 the die faces of which are hardened, ground,and parallel. Both die members have two parallel slots 59 across theirwidth and four shorter slots 60 extending lengthwise from these parallelslots to the edges of the die. A tongue or mandrel 61, which is hardenedand ground with parallel faces, is hinged to an end portion 62 of thelower die member 58, as on a pivot rod 63 extending through apertures 64in the end portion 62. The die members may be held in the press byscrews extending into the threaded apertures 65 in the upper member 57and 66 in the lower member 58.

The assembled anode is first inserted on the tongue 61, as shown in Fig.6. When the tongue 61 is lowered so that the anode section 14 isdirectly on top of the face of the lower die 58, the end flanges 53 fitinto the slots 59 and the ears 46 into the slots 60. The end flanges 53thus serve to position the assembly in the die. The upper die member isthen brought down pressing the anode assembly between the two die faces.

This operation results in the plate being squeezed to an insidedimension equivalent to the tongue thickness plus spring back. Since theonly support existing between the plate sections is that of the sixcolumns made up of the welded bosses, the plate is brought to propersize by crushing these columns. Thus the finished bumped plate assemblyis still practically free of stress in the flat areas of the plate,which were not affected by this bumping operation, and hence doesnotlose the minor axis dimensional accuracy in subsequent operations.

When the assembly is thus brought to proper size it is then treated witha black-body and gas absorbing coating, such as a zirconium hydride.

These steps in the preparation of an anode assembly in accordance withthis invention are diagrarned in Fig. 7, the steps being the making ofthe form plate blank and the bending of the flanges 53 and ears 46, thejoining of the two sections 13 and 14 together by welding theembossments 15 together, the hydrogen treatment of the welded assemblyto relieve stress, the bumping operation in a bumping die to accuratelyform the anode assembly, and the coating treated onto the anodeassembly.

When the anode is assembled in the tube the dimensions between it andthe other electrodes'are held to close tolerances by the design of theears 46 and the apertures 49 and 50. Motion of the anode assemblyperpendicular to the plane of the major axis of the cathode 16 isrestricted by the inside of ears 56 inserted in the apertures 49, 50.Motion parallel to the cathodes major axis is restricted by the ears 46and the apertures 50, these being formed with a close tolerance so thatthe ears 46 have an interference fit in the discs 23 and 24 while theears 46 located in apertures 49 are allowed to float in the apertures 49in this direction. This floating of the ears at one end of the anodeassembly permits of wider piece part tolerances in the dimensionsbetween the ears.

It is to be understood that the above-described arrangements areillustrative of the application of the principles of the invention.Numerous other arrangements may be devised by those skilled in the artWithout departing from the spirit and scope of the invention.

What is claimed is:

1. The method of preparing an electrode assembly for electron dischargedevices, said assembly comprising two similar fiat plate sections eachhaving inwardly extending embossments, comprising welding saidembossments, heat treating said assmebly to relieve stress, andsubsequent to said heat treatment compressing said assembly down to apredetermined spacing between said sections by crushing the weldedembossments.

2. The method of preparing an anode assembly for electron dischargedevices which comprises forming two anode sections with spaced inwardlyextending embossments adjacent parallel edges, placing the embossmentsof one section in abutting relation to those of the other section,locally welding said embossments together thereby to form a plurality ofspaced columns integral with the planar portions of said anode sectionsand extending therebetween, heat treating said assembly in a hydrogenatmosphere and bumping said assembly after said heat treatment bycompressing the welded embossments evenly to a predetermined spacingbetween sections.

3. The method of preparing an electrode assembly for electron dischargedevices comprising a pair of flat plate sections having inwardlyprojecting embossments adjacent parallel edges, which comprisespositioning the flat plate sections with the embossments of one plate inabutting relation to the embossments of the second plate, welding theabutting embossments together to form a plurality of columns integralwith said fiat plate sections and extending therebetween, heating theelectrode assembly in a hydrogen atmosphere, and applying pressureevenly to both sections to crush the columns to a predetermined spacingbetween sections subsequent to the heating of said electrode assembly.

References Cited in the file of this patent UNITED STATES PATENTS928,701 Rietzel July 20, 1909 1,430,634 Fischer Oct. 3, 1922 1,514,898Geisey Nov. 11, 1924 2,145,400 Loppacker Jan. 31, 1939

